TL;DR: WHM perspective on T10.
Your SCH should almost exclusively be handling the raises. The only exceptions are, of course, when the SCH dies.
I co-heal with a SCH and he will yell at me if I raise anyone unless he is OOM (which he shouldn't be) or he's dead.
Our Bard checks mana during each phase transition so when we started, yes, he most certainly did sing his mana song around the first set of adds and again on the second. We had SO many deaths initially so don't feel bad! Now he only sings at second set, I think.
As WHM I stand at the boss's left hind side at the edge of circle you fight him on. Our Bard stands directly to the side, also on the circle. Our SCH and other ranged are on the other side, similar spacing. This helps us avoid Heat Lightning hitting people extra people, including our 2 melee.
Critical Rip will come after a tail swipe so once you see the first tail swipe, Stoneskin and top off the tank ASAP.
For Charges, Stoneskin whomever is getting charged and toss them a regen.
After the first charge, I Swiftcast Medica 2 to top people off then hit Presence of Mind and start Stoneskinning the party again. Have your SCH focus on healing the tank until you're done. There will likely be a Prey put out before you're done so hopefully it will either hit someone you already Stoneskinned or you'll need to watch for it and toss a Stoneskin or SH will have to Adlo them ASAP.
You want stoneskin up on everyone before the first adds because Prey will be going out and this way, as a WHM, you can pretty much ignore it if you want for this round. The only people who don't get Stoneskin are the tanks because they're getting beat on by the adds anyway and won't get Prey. Your SCH may supplement with Adlo on Preyed people as needed, but our group doesn't seem to need it.
After this phase, we organize Prey protection having our party lists organized the same. I take top person, he takes bottom, unless one of us is Preyed, then we take care of our own selves while the other healer takes care of the other person.
For first adds, make sure your DPS aren't pulling them and getting hit before the tanks do. This removes their stoneskin, making them vulnerable to Prey, plus they take damage.
Eye for an Eye your tank once the adds pop and focus on them. SCH should focus on the other tank. Feel free to help out a little on both tanks, but you should mostly be able to handle healing your tank and they theirs unless they (the tanks) are derping and not using cooldowns.
Daughter then son on one group die, then daughter and son on 2nd group die. Our SCH DPSes when there's only 1 group left while I heal. Both add sets dead, we group on boss's butt and DPS, yes, even healers. Start counting as soon as last add is dead. Around 16 seconds I pop Divine Seal. When I see the Electric Burst bar hit the B in Burst, I cast Cure 3.
Don't bother Stoneskinning everyone here; Heat Lightning will remove it. Watch for Tethers and Charges. Medica 2 as needed. Stoneskin charged person and Regen. Watch for tail swipes and be ready with Stoneskins for the tank. Watch for tank swaps after/during charges. SCH should be handling Prey mechanics because Adlo has shorter cast time, but try to get Stoneskin off when you can. Just don't do it when it will sacrifice a tank or DPS.
2nd adds, Eye for Eye your tank and Presence of Mind Stoneskin who you can while you heal the tank. Watch for those Preys coming out and adjust accordingly.
When 2 set's left, I heal and SCH DPSes again. Adds die, start counting and DPS the boss. Be ready with a heal around 16.
Happy fun times- these take lots of coordination and practice. We number both healers and the melee (1, 2, 3, 4). Numbers only matter for Tether-Charge. The two lowest available numbers hug the Tether then everyone else runs in to help the Charged. For HL + Tether and HL + Charge it's wait for HL to go off, then whomever wasn't hit, runs to soak damage ASAP.
Critical Rip + Prey- SCH handles Prey while you handle Stoneskin and heals on tank.
Be prepared to start spamming Medica & Medica 2 towards the end if the group's DPS is low and the central circle fills. Toss a non-cleric Aero on the boss if you have the mana.
Anyone hit by Prey (actually affected, unprotected) or dying in the last phase = AOE from boss.